Synthesis of pyrylium salts containing a β-ketosulfonyl fragment

Article abstract of DOI:10.1134/S1070428015100073

Bis-acyl derivatives of diphenyl sulfide and diphenyl ether were synthesized by successive Friedel-Crafts acylations with 2-bromo-2-methylpropanoyl bromide and acetyl chloride. The subsequent reaction with sodium p-toluenesulfinate afforded the correspond

Full text of DOI:10.1134/S1070428015100073

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2015, Vol. 51, No. 10, pp. 1398–1403. © Pleiades Publishing, Ltd., 2015.
Original Russian Text © E.F. Kolchina, V.V. Shelkovnikov, 2015, published in Zhurnal Organicheskoi Khimii, 2015, Vol. 51, No. 10, pp. 1430–1435.
Synthesis of Pyrylium Salts
Containing a β-Ketosulfonyl Fragment
E. F. Kolchinaa, b and V. V. Shelkovnikova
a Vorozhtsov Novosibirsk Institute of Organic Chemistry, Siberian Branch, Russian Academy of Sciences,
pr. Akademika Lavrent’eva 9, Novosibirsk, 630090 Russia
b Novosibirsk State University, ul. Pirogova 2, Novosibirsk, 630090 Russia
e-mail: simfamily@yandex.ru
Received April 28, 2015
Abstract—Bis-acyl derivatives of diphenyl sulfide and diphenyl ether were synthesized by successive
Friedel–Crafts acylations with 2-bromo-2-methylpropanoyl bromide and acetyl chloride. The subsequent
reaction with sodium p-toluenesulfinate afforded the corresponding sulfones, and condensation of the latter
with benzaldehyde in acetic acid in the presence of perchloric acid gave pyrylium salts with a β-ketosulfonyl
fragment in the side chain.
DOI: 10.1134/S1070428015100073
Photoinitiated polymerization is widely used in
modern lithographic, UV and 3D printing, and holo-
graphic technologies. Photoinitiated radical polymer-
ization requires light-sensitive compounds that decom-
pose to generate free radicals. It is known that free
radicals are formed by photoinitiated fragmentation of
various β-keto sulfones via homolytic cleavage of the
α-C–C bond with respect to the carbonyl group [1].
The action of other initiating systems is based on
intermolecular transfer of an electron or hydrogen
atom or decomposition of a cationic center in the
initiator molecule (in cationic polymerization). Among
such initiators, sulfonium, iodonium, and quinolinium
salts have been reported [2]. A promising approach in
the design of photoinitiators implies combination of
two different photoinitiation centers in a single mole-
cule. Examples are photoinitiators containing a benzo-
phenone fragment and a ketosulfonyl group (Esacure
1001) [3] or a cationic sulfonium center and a keto-
sulfonyl group [4]. The activity of pyrylium salts in
photoinitiated polymerization has recently been
reported [5]. However, there are no published data on
photoinitiators containing both pyrylium moiety and
β-ketosulfonyl fragment.
A known method for the synthesis of pyrylium salts
is based on the condensation of α,β-unsaturated
ketones (chalcones) with carbonyl compounds [6].
β-Ketosulfonyl fragment may be assembled by
Friedel–Crafts acylation of an aromatic substrate with
2-bromo-2-methylpropanoyl bromide, followed by
replacement of bromine by a sulfonyl group. Insofar as
aromatic carbonyl compounds cannot be acylated
under Friedel–Crafts conditions, as aromatic substrates
we selected diphenyl sulfide (1a) and diphenyl ether
(1b) in which two benzene rings are separated by
a sulfur or oxygen bridge.
Introduction of two different acyl groups into the
para positions of diphenyl sulfide and diphenyl ether
has been reported in [7, 8]. Following an analogous
procedure, compounds 1a and 1b were subjected to
successive Friedel–Crafts acylation with 2-bromo-2-
methylpropanoyl bromide and acetyl chloride in meth-
ylene chloride in the presence of aluminum chloride
(Scheme 1). The first acylation with 2-bromo-2-
methylpropanoyl bromide was complete in one hour,
while subsequent introduction of acetyl group required
several days at room temperature. Bis-acyl diphenyl
sulfide 2a was thus obtained in almost quantitative
yield. The reaction with diphenyl ether (1b) was not as
selective as with 1a, and the reaction mixture con-
tained targeted unsymmetrical bis-acylated diphenyl
ether 2b together with small amounts of mono- and
The present work was aimed at developing a proce-
dure for the synthesis of pyrylium salts with a side-
chain β-ketosulfonyl group, i.e., compounds containing
two different potentially photoactive centers.
1398

SYNTHESIS OF PYRYLIUM SALTS CONTAINING A β-KETOSULFONYL FRAGMENT
1399
Scheme 1.
2
2'
7
Me
X
3
4
Me2C(Br)C(O)Br
AlCl3, CH2Cl2
MeC(O)Cl
AlCl3, CH2Cl2
3'
4'
X
1'
1
6'
6
5'
5
Me
· · ·
Br
Me
O
O
1a, 1b
2a, 2b
Me
O
O
Me
Me
+
+
Br
Me
Br
Me
Br
Me
O
O
O
X = S (a), O (b).
symmetrical bis-acyl derivatives which were isolated
by silica gel column chromatography and identified by
1H NMR [8, 9].
obviously due to –I effects of the acyl groups attached
thereto. There were three methyl and six CH signals in
the 13C NMR spectra of 3a and 3b. Replacement of the
bromine atom in 2 by toluenesulfonyl group led to
downfield shifts of the C6 (by 12–13 ppm) and C5 and
C4 signals (by 2–3 ppm), whereas the C7 signal shifted
by ~10 ppm upfield.
Reactions of alkyl halides with alkali metal sul-
finates are known to give the corresponding sulfones.
The reactions of 2a and 2b with sodium p-toluene-
sulfinate were carried out in different solvents [10, 11],
and the best results were obtained in DMF (Scheme 2).
The structure of 2a, 2b, 3a, and 3b was confirmed by
NMR, IR, and mass spectra and elemental analyses.
All these compounds displayed in the IR spectra strong
absorption bands due to stretching vibrations of the
carbonyl groups and conjugated C=C bond, and
characteristic SO2 bands were observed in the spectra
of 3a and 3b.
Our attempts to convert compounds 3a and 3b into
the corresponding chalcones as pyrylium salt precur-
sors by reaction with benzaldehyde in ethanol in the
presence of alkali were unsuccessful. According to the
1H NMR data, cleavage of the β-ketosulfonyl frag-
ment occurred, but the products were neither isolated
nor identified. Pyrylium salts 4a and 4b were synthe-
sized in 27 and 35% yield, respectively, by condensa-
tion of 3a and 3b with benzaldehyde in acetic acid in
the presence of 70% perchloric acid [11] (Scheme 3).
1
The H NMR spectra of 2a and 2b contained two
singlets from methyl groups with an intensity ratio of
2:1, and three methyl proton singlets with an intensity
ratio of 2:1:1 were present in the spectra of 3a and 3b.
The aromatic protons resonated as four (2a, 2b) or
six doublets (3a, 3b) with equal intensities, indicating
para substitution in each benzene ring of their
molecules.
Compounds 2a and 2b showed in the 13C NMR
spectra two methyl carbon signals, and the signal from
the carbon atom attached to bromine was displaced
by ~30 ppm downfield relative to the former. Aromatic
carbon signals appeared as four pairs of singlets, and
the largest difference in the chemical shifts was
observed for the C4 and C4′ atoms (ΔδC ≈ 3.0 ppm),
The structure of 4a and 4b was proved by NMR
1
and IR spectra and elemental analyses. Their H NMR
spectra contained two singlets in the region δ 1.5–
2.5 ppm with an intensity ratio of 2:1 (methyl groups)
and six doublets in the aromatic region, the latter cor-
responding to three different para-substituted benzene
rings. Aromatic protons of the tosyl group in 4a and 4b
resonated in the same regions as those of 3a and 3b,
and two protons in the pyrylium ring characteristically
gave a singlet at δ 8.5 ppm. Protons of the benzene
ring in the γ-position of the pyrylium ring appeared in
the spectrum as a doublet (o-H) and two triplets (p-H,
m-H) with an intensity ratio of 2:1:2.
Scheme 2.
12
Me
2
2'
10
7
Me
X
11
3
4
3'
4'
Me 9
SO2Na
1'
1
DMF
6'
8
2a, 2b
+
Me 5'
5
6
S
Me
O
O
O
O
3a, 3b
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 51 No. 10 2015

KOLCHINA, SHELKOVNIKOV
1400
Scheme 3.
CHO
3a, 3b
+
12
Me
11
2
2'
10
X
X
7
Me
Me
3
4
3'
4'
Me 9
Me
1'
1
Me
S
8
HClO4, AcOH
5
O
5'
6
S
O
O
O
O
6'
O
O
ClO4
7'
Ph
4a, 4b
In going from the 13C NMR spectra of 3a and 3b
to those of 4a and 4b, the largest upfield shift was
observed for the C4′ signals (ΔδC ≈ 9.5 ppm), while the
signals from C5′ and C6′, which constitute now the
pyrylium ring, displayed the largest downfield shifts
(by 27 and 87 ppm, respectively). The benzene ring in
the γ-position of the pyrylium ring gave rise to four
signals in the region δC 129–135 ppm.
The differences in the chemical shifts of 2-H, 2′-H,
3-H, and 3′-H in diphenyl sulfide derivative 4a and its
oxygen analog 4b are the same as for compounds 2
and 3. Replacement of sulfur in 3a and 4a by oxygen
(3b, 4b) is accompanied by downfield shift of the C1
and C1′ signals by 19–25 ppm, which may be due to
stronger negative inductive effect of the oxygen atom.
On the other hand, stronger +M effect of oxygen leads
to upfield shift of the C2, C2′ (by 10–12 ppm) and C4,
C4′ signals (by ~3 ppm). Molecules 3a and 4a are
characterized by higher degree of electron density
delocalization over the benzene rings linked through
the sulfur atom as opposed to 3b and 4b. The chemical
shifts of C8–C12 (tosyl group) are similar for all
compounds.
(a)
Emission
intensity, rel. units
D, rel. units
1.00
300
200
100
000
0.75
0.50
0.25
Pyrylium salts 4a and 4b showed luminescence.
Figure shows their absorption and luminescence spec-
tra in chloroform. Compounds 4a and 4b are charac-
terized by strong absorbance in the visible region and
are luminescent dyes. The absorption and lumines-
cence maxima of diphenyl sulfide derivative 4a
(λabs 507, λlum 611 nm) are located at longer wave-
lengths that those of its oxygen analog 4b (λabs 465,
0.00
300
400
500
600
700
800
900
λ, nm
(b)
Emission
intensity, rel. units
500
D, rel. units
1.0
400
300
200
100
000
λlum 535 nm). Triphenylpyrylium ion absorbs and emits
at shorter wavelengths (λabs 410 nm, λlum 460 nm) [12].
The appreciable shift of the absorption and lumines-
cence maxima depending on the presence of a hetero-
atom and is nature (O, S) in the substituents indicates
that they are conjugated with the aromatic system
of the pyrylium ring and are electron-donating toward
the latter.
0.5
0.0
In summary, we have synthesized pyrylium salts
containing β-ketosulfonyl fragments in the substit-
uents, which exhibit luminescence properties and are
potential photopolymerization initiators possessing
reaction centers of two different types.
200
300
400
500
600
700
800
λ, nm
Absorption and luminescence spectra of substituted pyrylium
salts (a) 4a and (b) 4b.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 51 No. 10 2015

SYNTHESIS OF PYRYLIUM SALTS CONTAINING A β-KETOSULFONYL FRAGMENT
1401
EXPERIMENTAL
(2H, 3-H, J = 8.6 Hz). 13C NMR spectrum (CDCl3), δC,
ppm: 26.5 (C6′), 31.5 (C7), 60.2 (C6), 129.2 (C2′), 129.8
(C2), 130.7 (C3′), 131.0 (C3), 133.2 (C4′), 135.8 (C4),
140.3 (C1′), 140.6 (C1), 195.5 (C5′), 197.1 (C5). Found:
m/z 376.0127 [M]+. C18H17BrO2S. Calculated:
M 376.0128.
The IR spectra were recorded on a Bruker Vector
1
22 spectrometer. The H and 13C NMR spectra were
1
measured on Bruker AV-300 SY (300.13 MHz for H)
and AM-400 instruments (400.13 MHz for 1H) relative
to the residual proton and carbon signals of the solvent.
The high-resolution mass spectra (electron impact,
70 eV) were obtained on DFS and Finnigan Mat 8200
mass spectrometers with direct sample admission into
the ion source (ion source temperature 314°C). The
electronic absorption and luminescence spectra were
recorded at room temperature from solutions in
chloroform on a Varian Cary Eclipse spectro-
fluorometer equipped with a xenon flash lamp
(luminescence measuring at an angle of 90°) using
10-mm quartz cells.
1-[4-(4-Acetylphenoxy)phenyl]-2-bromo-
2-methylpropan-1-one (2b). 2-Bromo-2-methylpro-
panoyl bromide, 2.2 mL (4.1 g, 17.8 mmol), was added
under stirring at room temperature to a solution of
2.8 mL (3.0 g, 17.6 mmol) of diphenyl ether (1b) in
10 mL of methylene chloride. The solution was cooled
to 5°C, and 2.4 g (18 mmol) of powdered anhydrous
aluminum chloride was added in portions over a period
of 20 min (each next portion was added after dissolu-
tion of the preceding one). The cooling bath was
removed, and the mixture was stirred for 20 min (the
temperature rose to ambient) and then for 1 h at room
temperature. The mixture was cooled to 5°C, 1.3 mL
(1.42 g, 18 mmol) of acetyl chloride was added, and
2.4 g (18 mmol) of aluminum chloride was then added.
The cooling bath was removed, and the mixture was
stirred for 3 h and kept for 3 days at room temperature.
The dark brown viscous solution was poured into
a mixture of 100 g of ice with 5 mL of concentrated
aqueous HCl and 15 mL of methylene chloride under
vigorous stirring. The organic phase was separated, the
aqueous phase was extracted with methylene chloride,
the extract was combined with the organic phase,
washed with water, and dried over CaCl2, and the
solvent was distilled off. The residue, 6.6 g, was a dark
thick oily material. It was dissolved in 5 mL of meth-
ylene chloride and subjected to column chromatog-
raphy on silica gel (50–160 μm) using methylene
chloride–petroleum ether (bp 70–100°C; 1:1) as
eluent. Yield 4.40 g (69%). IR spectrum (KBr), ν,
cm–1: 3065, 2976, 2930, 2876, 1672, 1647, 1593, 1504,
1360, 1304, 1263, 1223, 1200, 1165, 1111, 980, 961,
1-[4-(4-Acetylphenylsulfanyl)phenyl]-2-bromo-
2-methylpropan-1-one (2a). 2-Bromo-2-methylpro-
panoyl bromide, 3.8 mL (7.13 g, 31 mmol), was added
under stirring at room temperature to a solution of
5.0 mL (5.57 g, 30 mmol) of diphenyl sulfide (1a) in
20 mL of methylene chloride. The mixture was cooled
to 5°C, and 4.14 g (31 mmol) of powdered anhydrous
aluminum chloride was added in portions over a period
of 20 min (each next portion was added after dissolu-
tion of the preceding one). The cooling bath was
removed, and the mixture was stirred for 20 min to
allow it to warm up to room temperature and was then
stirred for 1 h at room temperature. The mixture was
cooled to 5°C, 2.4 mL (2.60 g, 33 mmol) of acetyl
chloride was added, and 4.40 g (33 mmol) of alumi-
num chloride was then added. The cooling bath was
removed, and the mixture was stirred for 3 h and then
kept for 4 days at room temperature. The dark brown
viscous solution was poured into a mixture of 150 g of
ice with 5 mL of concentrated aqueous HCl and
20 mL of methylene chloride under vigorous stirring.
The organic layer was separated, and aqueous layer
was extracted with methylene chloride. The extract
was combined with the organic phase, washed with
water, and dried over CaCl2, and the solvent was
distilled off. Yield 10.9 g (96%), oily material; the
product was used without additional purification. IR
spectrum (film), ν, cm–1: 3060, 3005, 2974, 2928,
1680, 1585, 1555, 1458, 1398, 1358, 1167, 1105,
1
862, 837, 590, 582. H NMR spectrum (CDCl3), δ,
ppm: 2.02 s (6H, CH3), 2.57 s (3H, CH3), 7.03 d (2H,
2-H, J = 9.0 Hz), 7.08 d (2H, 2′-H, J = 8.9 Hz), 7.96 t
(2H, 3′-H, J = 8.9 Hz), 8.21 d (2H, 3-H, J = 9.0 Hz).
13C NMR spectrum (CDCl3), δC, ppm: 26.1 (C6′), 31.1
(C7), 59.9 (C6), 117.7 (C2′), 118.4 (C2), 129.5 (C4′),
130.3 (C3′), 132.3 (C3), 132.6 (C4), 159.2 (C1′), 159.5
(C1), 194.4 (C5′), 196.0 (C5). Found: m/z 360.0349
[M]+. C18H17BrO3. Calculated: M 360.0356.
1
1084, 1011, 980, 957, 885, 824, 621, 592. H NMR
1
spectrum (CDCl3), δ, ppm: 1.99 s (6H, CH3), 2.56 s
(3H, CH3), 7.33 d (2H, 2-H, J = 8.6 Hz), 7.40 d (2H,
2′-H, J = 8.5 Hz), 7.87 d (2H, 3′-H, J = 8.5 Hz), 8.08 d
According to the H NMR data [8, 9], the product
contained 2-bromo-2-methyl-1-(4-phenoxyphenyl)-
propan-1-one (0.63 g, 11%) and 2-bromo-1-{4-[4-(2-
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 51 No. 10 2015

KOLCHINA, SHELKOVNIKOV
1402
bromo-2-methyl-1-oxopropyl)phenoxy]phenyl}-
2-methylpropan-1-one (0.34 g, 4%).
(2H, 2-H, J = 8.8 Hz), 7.30 d (2H, 10-H, J = 8.0 Hz),
7.63 d (2H, 9-H, J = 8.0 Hz), 7.98 d (2H, 3′-H, J =
8.8 Hz), 8.07 d (2H, 3-H, J = 8.8 Hz). C NMR spec-
13
1-{4-[(4-Acetylphenyl)sulfanyl]phenyl}-2-
methyl-2-(4-methylbenzenesulfonyl)propan-1-one
(3a). Sodium p-toluenesulfinate, 1.0 g (5.6 mmol), was
added in portions over a period of 1 h under stirring to
a solution of 1.9 g (5.0 mmol) of compound 2a in
7 mL of DMF, and the mixture was stirred for 2 h at
room temperature. The mixture was poured into
100 mL of water and extracted with methylene
chloride, the extract was dried over CaCl2, the solvent
was distilled off, and the residue was subjected to
column chromatography on silica gel (50–120 μm)
using petroleum ether (bp 70–100°C) as eluent.
Removal of the solvent from the main fraction gave
1.48 g (75%) of 3a as a thick oily material which was
used without additional purification. IR spectrum
(film), ν, cm–1: 3062, 2978, 2937, 2871, 1682, 1585,
1557, 1456, 1398, 1358, 1313, 1302, 1261, 1151,
trum (CDCl3), δC, ppm: 21.5 (C7), 22.5 (C12), 26.3
(C6′), 73.2 (C6), 118.1 (C2′), 118.6 (C2), 129.2
(C9), 130.0 (C3′), 130.5 (C10), 131.7 (C3), 132.0 (C8),
132.8 (C4′), 132.9 (C4), 141.1 (C11), 159.2 (C1′), 159.8
(C1), 196.4 (C5′), 196.9 (C5). Found, %: C 69.30;
H 5.52; S 7.23. C25H24O5S. Calculated, %: C 68.78;
H 5.54; S 7.35.
2,6-Bis[4-({4-[2-methyl-2-(4-methylbenzenesul-
fonyl)-1-oxopropyl]phenyl}sulfanyl)phenyl]-4-phe-
nylpyrylium perchlorate (4a). Compound 3a, 0.50 g
(1.1 mmol), was dissolved in 0.70 mL of glacial acetic
acid under stirring for 0.5 h at room temperature,
0.07 mL (0.073 g, 0.7 mmol) of benzaldehyde was
added, and 0.18 mL of 70% HClO4 was then added
dropwise. The mixture was heated for 1 h at 60°C and
kept for 60 h at room temperature. The mixture was
then poured into 100 mL of diethyl ether under
stirring, and a dark red oily material separated. The
ether solution was separated by decanting, the oily
residue was dissolved in methylene chloride, the
solution was passed through a layer of silica gel (50–
160 μm, h = 35 mm, d = 40 mm), and the sorbent was
washed with methylene chloride until complete elution
of a yellow fraction. The red substance that remained
adsorbed on silica gel was eluted with acetonitrile.
Removal of the solvent gave 0.16 g (27%) of a dark
red crystalline substance which was purified by repre-
cipitation from methylene chloride with diethyl ether.
IR spectrum (KBr), ν, cm–1: 3061, 2924, 1674, 1622,
1587, 1491, 1460, 1300, 1290, 1248, 1150, 1126,
1080, 1010, 968, 833, 818, 768, 710, 623, 600.
1H NMR spectrum (CD3CN), δ, ppm: 1.63 s (12H,
CH3), 2.45 s (6H, CH3), 7.42 d (4H, 10-H, J = 8.2 Hz),
7.55 d (4H, 2-H, J = 8.4 Hz), 7.64 d (4H, 2′-H, J =
8.4 Hz), 7.68 d (4H, 9-H, J = 8.2 Hz), 7.73 t (2H, m-H,
J = 7.5 Hz), 7.82 t (1H, p-H, J = 7.5 Hz), 7.94 d (4H,
3-H, J = 8.4 Hz), 8.25 d (2H, o-H, J = 7.5 Hz), 8.29 d
(4H, 3′-H, J = 8.4 Hz), 8.60 s (2H, 6′-H). 13C NMR
spectrum (CDCl3), δC, ppm: 21.4 (C7), 22.3 (C12), 73.0
(C6), 113.6 (C6′), 125.6 (C4′), 128.8–130.0 (C2, C2′, C3′,
C9, C10, Co, Cm, Cp), 131.5 (C4), 131.6 (C1′), 132.1 (C3),
135.9 (C8), 137.3 (Ci), 145.2 (C11), 146.9 (C1), 164.5
(C7′), 168.7 (C5′), 197.9 (C5). Found, %: C 64.32;
H 4.5; Cl 3.14; S 11.20. C57H49ClO11S4. Calculated, %:
C 63.76; H 4.60; Cl 3.30; S 11.95.
1
1130, 1080, 968, 957, 820, 712, 671, 600. H NMR
spectrum (CDCl3), δ, ppm: 1.66 s (6H, CH3), 2.42 s
(3H, CH3), 2.57 s (3H, CH3), 7.30 d (2H, 10-H, J =
8.2 Hz), 7.36 d (2H, 2-H, J = 5.7 Hz), 7.40 d (2H, 2′-
H, J = 5.7 Hz), 7.63 d (2H, 9-H, J = 7.2 Hz), 7.88 d
(2H, 3′-H, J = 8.1 Hz), 7.93 d (2H, 3-H, J = 8.4 Hz).
13C NMR spectrum (CDCl3), δC, ppm: 21.3 (C7), 22.3
(C12), 26.1 (C6′), 73.0 (C6), 128.9 (C9), 129.1 (C10),
129.7 (C2′), 129.8 (C2), 130.0 (C3′), 130.3 (C3), 131.8
(C8), 135.6 (C4′), 136.0 (C4), 139.6 (C1′), 140.4 (C1),
145.0 (C11), 196.7 (C5′), 197.5 (C5). Found: m/z
452.1102 [M]+. C25H24O4S2. Calculated: M 452.1111.
1-[4-(4-Acetylphenoxy)phenyl]-2-methyl-
2-(4-methylbenzenesulfonyl)propan-1-one (3b).
Sodium p-toluenesulfinate, 1.2 g (6.7 mmol), was
added in portions over a period of 1 h under stirring to
a solution of 2.13 g (6.0 mmol) of compound 2b in
15 mL of DMF, and the mixture was stirred for 3 h at
room temperature. The mixture was poured into
100 mL of water and extracted with methylene
chloride, the extract was dried over CaCl2, the solvent
was distilled off, and the residue was washed with
hexane to obtain 2.4 g (73%) of 3b as an oily crystal-
line material which was used without additional puri-
fication. mp 98–99°C [from petroleum ether (70–
100°C)–EtOH, ~1:1]. IR spectrum (KBr), ν, cm–1:
3067, 3001, 2980, 2926, 1695, 1660, 1587, 1497,
1302, 1265, 1234, 1170, 1151, 1128, 1180, 980, 959,
1
871, 862, 840, 819, 667, 586. H NMR spectrum
2,6-Bis(4-{4-[2-methyl-2-(4-methylbenzenesul-
fonyl)-1-oxopropyl]phenoxy}phenyl)-4-phenylpyr-
ylium perchlorate (4b). Compound 3b, 0.44 g
(CDCl3), δ, ppm: 1.68 s (6H, CH3), 2.43 s (3H, CH3),
2.59 s (3H, CH3), 7.05 d (2H, 2′-H, J = 8.8 Hz), 7.08 d
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 51 No. 10 2015

SYNTHESIS OF PYRYLIUM SALTS CONTAINING A β-KETOSULFONYL FRAGMENT
1403
(1.0 mmol), was dissolved in 1.5 mL of glacial acetic
acid under stirring for 0.5 h at room temperature,
0.06 mL (0.06 g, 0.6 mmol) of benzaldehyde was
added, and 0.12 mL of 70% HClO4 was then added
dropwise. The mixture was heated for 3 h under reflux,
cooled to room temperature, and poured into 100 mL
of diethyl ether under stirring. A dark red oily material
separated, the diethyl ether solution was separated by
decanting, the oily residue was dissolved in methylene
chloride, and the solution was passed through a layer
of silica gel (50–160 μm, h = 35 mm, d = 30 mm). The
sorbent was washed with methylene chloride until
complete elution of a light yellow fraction, and the
yellow material that remained adsorbed on silica gel
was eluted with acetonitrile. Removal of the solvent
left 0.18 g (35%) of a yellow crystalline substance
which was purified by reprecipitation from methylene
chloride with diethyl ether, mp 147–148°C. IR spec-
trum (KBr), ν, cm–1: 3067, 2927, 1672, 1624, 1591,
1494, 1462, 1300, 1290, 1246, 1173, 1150, 1123, 1107,
The spectral and analytical data were obtained at
the Joint Chemical Service Center, Siberian Branch,
Russian Academy of Sciences.
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1
1080, 968, 843, 770, 714, 673, 623, 590. H NMR
spectrum (CD3CN), δ, ppm: 1.65 s (12H, CH3), 2.45 s
(6H, CH3), 7.24 d (4H, 2-H, J = 8.8 Hz), 7.35 d (4H,
2′-H, J = 8.8 Hz), 7.42 d (4H, 10-H, J = 8.2 Hz), 7.67 d
(4H, 9-H, J = 8.2 Hz), 7.74 t (2H, m-H, J = 7.4 Hz),
7.82 t (1H, p-H, J = 7.4 Hz), 8.05 d (4H, 3-H, J =
8.8 Hz), 8.26 d (2H, o-H, J = 7.4 Hz), 8.43 d (4H,
3′-H, J = 8.8 Hz), 8.57 s (2H, 6′-H). 13C NMR spec-
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(C6), 113.4 (C6′), 119.2 (C2′), 119.6 (C2), 123.3 (C4′),
129.3 (Cp), 129.4 (C9), 129.7 (Cm), 130.0 (Co), 130.2
(C3), 131.2 (C10), 131.8 (C8), 132.1 (C3′), 134.9 (Ci),
145.3 (C11), 157.8 (C1′), 162.6 (C1), 164.8 (C7′), 169.0
(C5′), 197.1 (C5). Found, %: C 65.94; H 4.54; Cl 3.10;
S 5.97. C57H49ClO13S2. Calculated, %: C 65.73;
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